This invention relates to radiographic analysis. The invention relates more particularly to means for testing the operating characteristics of a tomographic analytical apparatus.
Tomography, as is well known, is a medical technique of radiographic analysis which provides an image of a particular plane of a body under examination. In one form of tomographic instrument, an X-ray source and an X-ray detector are positioned in alignment on opposite sides of a subject under examination and simultaneously scan an edge of a cross sectional plane or a slice of finite thickness extending through the subject. Intensity of X-ray transmission through the subject is determined by sampling an electrical output of the detector at a number of equally spaced positions in a single scan direction. Sampling occurs, for example, at about 160 different locations in the direction of a single scan. The X-ray source and detector are then rotated a predetermined angular distance about an axis normal to the plane or slice through the subject and another scanning of the edge in a different direction is obtained. In a form of this apparatus particularly adapted for examination of a patient's head, a scan occurs for each 1.degree. of angular rotation. Resultant data is processed by a computer to reconstruct an image of the planar cross section or slice through the patient's head.
It is desirable at times to verify that the operation of a scanning tomographic instrument of the type described conforms with its known capabilities. In addition, it is desirable to predetermine the capabilities of the instrument for the performance of specific examinations.
Accordingly, it is an object of this invention to provide an improved means for testing the operation of a scanning, tomographic instrument.
Another object of the invention is to provide an improved phantom for verifying operating characteristics of a scanning tomographic instrument.
Another object of the invention is to provide a phantom simulating a human head and having means for verifying a plurality of operating characteristics of a scanning tomographic instrument.